The present invention relates to a mobile protective cover for an open zone of a machine tool or similar type of machine, with working parts moving on the area defined by said zone.
The present cover is, in particular, attached to a working part or tool on the machine, which is mobile along an operating path, preferably extending in accordance with at least two reference coordinates and, in particular, extending in a plane that is substantially parallel to the plane in which the area lies.
Covers of this type are used mainly to stop dirt, shavings, chippings, machining emulsions and other extraneous matter from getting into the working area and preventing correct machine operation.
These protective covers basically comprise a plurality of cover elements consisting of substantially flat plates placed in contact with each another. One of the plates is rigidly fixed along the corresponding edges of the machine forming the above mentioned working area, and can act as a support for the other plates which slide relative to each other.
The perimetric dimensions of the fixed plate are such that it completely covers the open zone and has an opening which gives the plate the shape of a frame. The dimensions of the opening are substantially equal to the area in which the mobile tool is designed to move, defining the maximum travel possible for the tool along the two coordinates.
Starting with the fixed plate, the size of the other mobile plates gradually decreases down to the last and smallest plate in the set, which is attached to the mobile tool. The shape of each plate is similar to that of the others and each has a respective opening, giving it the shape of a frame similar to that of the fixed plate. The outer and inner perimetric dimensions of each frame-shaped plate are similar to the outer and inner perimetric dimensions of the larger and smaller plates adjacent to it.
Each plate is kinematically connected to the others and its size complements that of the plates adjacent to it in such a way that, following a movement of the tool along the above mentioned path, the plate attached to it drives the other plates along behind it, and these slide over one another, keeping the area of the above-mentioned zone closed and protected during the working movements of the tool. In this way, the cover protects the machining tool support and drive parts extending towards the inside of the machine.
The drive movements between the plates are transmitted by means of transmission mechanisms, such as chains and corresponding toothed wheels, or four-bar linkages, with extremely complex and difficult operation, especially if the tool moves at high speeds. Moreover, such types of mechanisms are costly, require long assembly times, and make the covers cumbersome and unwieldy.
Another disadvantage of known protective covers of this kind is that they are unable to support heavy weights resulting from the increasingly large machine tools and machining centers of the latest generation. Indeed, on account of their constructional characteristics and particularly complex mechanisms, these covers become useless when their size and weight exceed certain limits. The excessive weight of the mobile elements causes deformation and breakage of the transmission mechanisms, resulting in seizure and jamming of the mobile elements and creating dangerous situations.
The main aim of the present invention is to overcome the disadvantages of the protective covers made according to the teachings of prior art and to provide a protective cover of new design that can be attached to a mobile working part and that is economical and easy to construct while at the same guaranteeing trouble-free operation even if it is considerably large and heavy.
Accordingly, the invention as described in the claims below provides a protective cover for a machine zone with moving parts, where the machine comprises a frame and a working part which can move, relative to the frame, along an operating path. The protective cover comprises a plurality of cover elements, including at least one cover element which can be connected to the machine frame, a mobile cover element connected to the working part of the machine and, if necessary, one or more mobile intermediate cover elements, located between the fixed cover element and the mobile cover element. The cover elements have respective cover panels which extend substantially in a single plane, parallel to a defined placement plane, and each of which has a central opening in it. The cover elements are arranged in order of decreasing size, are positioned around the working part and are connected to the working part in such a way as to follow its movements, keeping the machining zone covered. Means are provided to support the mobile cover elements connected to the fixed cover element. The novel aspect of the protective cover made according to the present invention lies in that said support means comprise at least one first support rod and one second support rod, which are at a given distance from each other and which also constitute means for guiding the movement of the mobile elements in a first direction parallel to, and a second direction at right angles to, the rods themselves.
The use of such support and guide rods overcomes the disadvantages created by the insufficient rigidity of the protective covers known up to now and eliminates the need for complex transmission chains, toothed wheels and four-bar linkages, with appreciable advantages in terms of simpler construction and operation of the cover provided by the present invention, even if the cover is considerably large and heavy.